Process of and apparatus for making three-dimensional objects

Abstract

Process for obtaining three-dimensional objects, according to which process a sheet (2A, 2B, 2C) is prepared, which sheet is composed of a material, the solubility of which varies when it is subjected to a specific radiation, and of fibers or of a screen for reinforcement, the sheet having a sufficient rigidity to be handled and being capable of adhering on a similar sheet. The sheet is subjected to said radiation (18) in a defined zone, and then a new sheet is fixed onto it and the passing of radiation is recommenced, and then the stack is subjected to a selective dissolving which causes the desired object (31) to appear.

We claim: 
     
       1. A process for the production of objects of defined shape, comprising the following steps: a) providing at least one thin layer which, when it is subjected to a defined radiation, undergoes a change of solubility in at least one specified solvent, accompanied by a change of volume less than a predetermined limit,   b) reinforcing at least one of said thin layers with fibers or with a screen,   c) scanning said first thin layer with a beam of said radiation, according to a trace specified in advance and under conditions of intensity and of duration which are capable of causing said change of solubility,   d) providing a second thin layer of the same material and superposing it on the first,   e) scanning said second thin layer with a beam of the same radiation, according to a trace such that and under conditions such that said change of solubility occurs in the second layer and that the volume of the second layer which is affected by said change of solubility is capable of forming at least one volume continuous with that volume of the first layer which has been previously affected by said change of solubility,   f) causing the adhesion of said second layer on the first layer, at least in the region of these two layers which, after their respective irradiation, have the lowest solubility, in such a manner as to constitute a continuous volume of material having lower solubility,   g) repeating the operations d) to f) until the volumes of material having lower solubility of the successive layers constitute together an integral unitary volume having the shape of the desired object,   h) placing the stack formed by the superposed successive layers in contact with said solvent in such a manner as to separate the parts of material having lower solubility from the parts of material having higher solubility, wherein step f) occurs before the step e) of after the step g).   
     
     
       2. The process of claim 1, wherein, in order to reinforce said thin layer, there are incorporated therein, while the material is in a pasty condition, short fibers forming a sheet of non-woven product. 
     
     
       3. The process of claim 1, wherein, in order to reinforce said thin layer, a screen is incorporated therein while the material is in a pasty condition. 
     
     
       4. The process of claim 3, comprising the use of a screen, wherein the screen exhibits projections perpendicular to its plane, projecting outside said thin layer, and designed to cooperate with the screen of an adjacent layer, constituting a three-dimensional reinforcement. 
     
     
       5. The process of claim 3, wherein there are incorporated in said thin layer additional rigid parts which form projections beyond the surface of the layer and are designed to cooperate with fibers or a screen incorporated into said thin layer and with fibers or a screen incorporated into an adjacent thin layer in order to construct a three-dimensional reinforcement. 
     
     
       6. The process of claim 1, wherein said material capable of a change of solubility contains an inert filler. 
     
     
       7. The process of claim 1 wherein said material undergoes a volume variation of less than 2% when it receives said radiation. 
     
     
       8. The process of claim 1 including removal of the fibers or the screen which, after the step g), project outside a non-dissolved volume, by dissolving or chemical attacking the fibers or the screen by means of a substance which does not act on said non-dissolved volume. 
     
     
       9. The process of claim 1 wherein in the case where, from one layer to another of the object to be constructed, an area of a cross section to be scanned by said radiation exhibits large variations, there are provided compensation zones such that the total scanned surface area shows no more than slight variation from one layer to the other. 
     
     
       10. The process of claim 1, wherein the object which it is desired to procure includes cavities which are closed or which communicate with the exterior via confined passages, said integral unitary volume is formed with broadened or supplementary passages for the communication of said cavities with the exterior, in order to permit a less restricted circulation of the solvent. 
     
     
       11. An apparatus for carrying out the process according to claim 1, comprising: means for forming a continuous strip of said material, reinforced by a screen,   means for directing said strip towards a treatment station,   means for cutting the strip into unitary sheets and for superposing each sheet on a previously treated sheet, in adhesion contact,   treatment means comprising a radiation source capable of passing said radiation to a defined point of the sheet, means for detecting a position of the sheet and means for displacing said point as a function of said position of the sheet, and   means for directing a block formed by a superposition of treated sheets to an installation for dissolving the high-solubility part of the material.   
     
     
       12. An apparatus for carrying out the process according to claim 1 comprising: means for forming a continuous strip of said material, reinforced by a screen,   means for directing said strip towards a treatment station,   a rotatable support on which said strip is to be wound,   treatment means comprising a radiation source capable of passing said radiation to a defined point of the wound strip, means for detecting the position of an impact point of the radiation on the wound strip and means for displacing said impact point as a function of a location of said wound strip, and   means for separating from the rotatable support a block formed by the wound strips and for directing the block to an installation for dissolving the low-solubility part of the material.   
     
     
       13. The apparatus of claim 11 wherein said installation dissolves not only the high solubility part of the material but also the remaining fraction of the screen. 
     
     
       14. The process of claim 10 including the additional step of subsequently filling the passages.